1. Field of the Invention
The present invention relates generally to the treatment of disorders which receive blood flow from the uterine arteries, and more particularly to methods for the non-permanent occlusion of the uterine artery or arteries, including for use in treating uterine myomata (fibroids), dysfunctional uterine bleeding (DUB), post partum hemorrhaging (PPH), and uterine bleeding associated with cesarian section surgery.
2. Brief Description of the Related Art
Hysterectomy (surgical removal of the uterus) is performed on approximately 600,000 women annually in the United States. For approximately 340,000 women, hysterectomy is probably the best current therapeutic choice for the treatment of their diseases (uterine cancer, endometriosis, menorrhagia, and prolapse). For approximately 60,000 women with dysfunctional uterine bleeding (abnormal menstrual bleeding that has no discrete anatomic explanation such as a tumor or growth), newer endometrial ablation techniques may be an alternative to hysterectomy. For approximately 200,000 women with benign but symptomatic (excessive bleeding, pain, and “bulk” sensations) muscular tumors of the uterus, known as leiomyoma or fibroids, newer treatment methods have been developed which may spare these women a hysterectomy, as well.
Hysterectomy for treating uterine fibroid disorders, though effective, has many undesirable characteristics. Thus, any method which can approximate the therapeutic result of a hysterectomy without removing the uterus (and commonly the ovaries since they are closely adjacent to the uterus) would be a significant improvement in this field.
The undesirable characteristics of hysterectomy include a known mortality rate of 0.5 deaths per 1000 hysterectomies. Stated another way, the risk of death within 30 days of hysterectomy is thirty times greater for women who have had a hysterectomy than for women of similar ages and backgrounds who have not had a hysterectomy. Morbidity (medical symptoms and problems short of death) associated with hysterectomy include possible injury to adjacent organs (the bladder, the ureters, and bowel), hospital stay of approximately one week, five to six weeks of slow recovery to normal activity, three weeks of absence from work, direct medical expenses of at least $10,000, indirect cost of time away from work, a future three-fold increase in the incidence of cardiovascular disease, decreased sexual pleasure in approximately thirty percent of women, and depression and anxiety for many years after the hysterectomy for approximately eight percent of women.
Surgically removing fibroids (myomectomy) or in situ ablation of uterine fibroids is a bit like eradicating ants in the pantry—they are not all seen from one perspective and there may be a lot of them. Commonly, a diagnosis of uterine fibroids involves the presence of multiple fibroids, often averaging ten fibroids or more per afflicted uterus. Consequently, it is difficult to know which fibroid is causing symptoms to the patient (bleeding, pain, and bulk effects on adjacent organs). Furthermore, fibroids occur at different layers in the uterus. Uterine fibroids can occur adjacent to the lining of the uterus (submucosal fibroid), in the myometrium (intramural fibroid), or adjacent to the outer layer of the uterus (subserosal fibroid). Consequently, if one is directly observing the uterus from the peritoneal cavity, only subserosal fibroids would be seen. If one is directly observing the uterus from the endometrial surface of the uterus, only the submucosal would be seen. Fibroids deep within the wall of the uterus are poorly visualized from either surface. Finally, since fibroids come in all sizes, only the larger fibroids will be seen in any case.
Clearly, the strategy of identifying which individual fibroid is causing symptoms (when there are often many), finding that fibroid, and then either removing or destroying that individual fibroid is a rather complex strategy. It is therefore easy to understand why the hysterectomy is such a common surgical choice. With hysterectomy, all uterine fibroids are removed in one stroke.
In 1995, it was demonstrated that fibroids, in a uterus that contained one or multiple fibroids, could be treated without hysterectomy using a non-surgical therapy, specifically comprising bilateral intraluminal occlusion of the uterine arteries (Ravina et al., “Arterial Embolization to Treat Uterine Myomata”, Lancet Sep. 9, 1995; Vol. 346; pp. 671–672, incorporated by reference in its entirety herein). This technique is known as “uterine artery embolization”. The technique uses standard interventional radiology angiographic techniques and equipment, whereby the uterine arteries are accessed via a transvascular route from a common femoral artery into the left and right uterine arteries.
Three facts explain the success of uterine artery embolization. First, it has been established that pelvic bleeding from a wide variety of sources (e.g., auto accidents, surgical errors, and post partum hemorrhage) can be effectively controlled with embolization techniques using coils placed in arterial and venous lumens (U.S. Pat. Nos. 4,994,069, 5,226,911, and 5,549,824, all of which are incorporated in their entireties herein) (available from Target Therapeutics), or particles (GELFOAM pledgets, available from Upjohn, Kalamazoo, Mich., or IVALON particles, available from Boston Scientific).
Second, fibroids live a tenuous vascular life with very little ability to recruit a new blood supply from the host when the primary blood supply is compromised. Third, the uterus has a dual (or redundant) blood supply; the primary blood supply is from the bilateral uterine arteries, the secondary blood supply from the bilateral ovarian arteries.
Consequently, when both uterine arteries are occluded, i.e., bilateral vessel occlusion, the uterus and the fibroids contained within the uterus are both deprived of their blood supply. However, as demonstrated by Ravina et al., the effect on the fibroid is greater than the effect on the uterus. In most instances, the fibroid withers and ceases to cause clinical symptoms.
The uterine artery embolization technique utilized by Ravina et al. uses standard transvascular equipment, available in a typical interventional radiology angiography suite. This equipment includes guide catheters to selectively enter the tortuous right and left uterine arteries, Ivalon or Gelfoam particles, and intravascular coils. With skill and these standard angiographic tools, the uterine arteries can be occluded bilaterally and fibroid disease treated through a 2 mm hole in the right groin and through the right common femoral artery. Following the procedure, the arterial puncture site is held with manual pressure for fifteen minutes. While post-procedural pain is often significant, and requires intravenously delivered pain medication, the patient is typically fully recovered in a number of days.
The problem with uterine artery embolization is simple. The physicians who know how to do the procedure are interventional radiologists, who do not take care of gynecology problems. The physicians who take care of gynecology problems do not possess the skill necessary to perform catheter-based uterine artery embolization. Accordingly, only on the order of tens of thousands of uterine artery embolizations have been performed, worldwide, since approximately 1995, whereas hundreds of thousands of hysterectomies have been performed each year for uterine fibroids which are symptomatic.
Currently, many physicians continue to embolize the uterine artery with PVA particles. As reported by the Society for Cardiovascular and Interventional Radiology in late 1999, some 6000 cases have been performed within the United States. Currently the annualized run rate for this procedure is approximately 4500 cases per year.
Previously, physicians have permanently, surgically ligated the uterine artery utilizing metal vascular clips. This procedure has been performed laparoscopically and requires a great deal of surgical skill to access, identify, dissect, and ligate the uterine arteries. This requirement for high skill and a full surgical approach has limited the use of surgical ligation of the uterine arteries as a clinical alternative for uterine fibroid treatment.
The current treatments offered to women focus on permanent or near permanent occlusion methods for the uterine artery. These methods include (the expected longevity of the embolic agent is given parenthetically): embolizing with PVA particles (6 months to permanent in situ); embolizing with stainless steel coils (permanent in situ); embolizing with Gelfoam (3 to 4 weeks before degradation of the embolic particles); surgical ligation with metal vascular clips (permanent); and surgical ligation with RF ablation (permanent).
All of the prior art devices and methods are therefore aimed at permanent occlusion of the uterine artery, resulting in redirection of the blood flow to the uterus through collateral circulation. The patients which suffer most dramatically from uterine myomata are women of child bearing age who may desire to bear additional children. The current methods of embolizing or ligating uterine arteries are specifically contraindicated for women who desire to bear additional children. This is the realization of inadequate blood supply to the uterus because of the loss of the uterine arteries, the primary blood supply. A few reports have been cited of women who have undergone uterine artery embolization with PVA particles and then gone on to become pregnant and deliver normal babies. Reports have also been cited of women who have experienced premature menopause due to ovarian failure from these same procedures.
While it is apparent that uterine artery embolization with the current embolic agents or ligation techniques is effective for treating uterine myomata, it is also apparent from a review of case reports and complications that this treatment is in need of a substantial improvement in safety.
The tissue of the vaginal wall is very elastic, pliable, and flexible. The vaginal wall can made to assume different shapes without tearing and without significant patient discomfort or pain. Heretofore, this inherent characteristic of these tissues has not been utilized in the treatment of myomata, or for accessing the uterine artery. Instead, prior techniques have relied upon transvascular routes (Ravina et al.), complete surgical or laparoscopic dissection of the tissues surrounding a uterine artery to achieve access to the vessel. The difficulty and cost associated with the use of traditional transvascular access, and the possibility of infection and surgical complication associated with dissection, render these prior techniques unacceptable.
Those of skill in the art are well acquainted with DUB, PPH, and cesarian section-related bleeding. While the causes of DUB are often not identified, current treatments include endometrial ablation and hysterectomy, which can be extreme treatments for some patients. PPH and cesarian section-related bleeding can be a dangerous if not quickly and adequately controlled, which may require a fast surgical response, from which the patient may suffer from associated trauma of the surgery.
Another aspect of hysterectomy procedures is that the blood supply to the uterus is typically stopped by ligating the uterine arteries, to prevent the patient from bleeding excessively as the uterus is removed. This ligation task can be very laborious and time-consuming, as the arteries are dissected and ligated by the surgeon, and have associated complications.
There therefore still remains a need in the art for improvements in methods, processes, and techniques for occluding the uterine arteries for treatment of numerous conditions and/or facilitating other procedures.